1. Field of the Invention
The present invention relates generally to microstrip antennas. More specifically, the present invention relates to a microstrip antenna having an internal electrical feed point which allows the antenna to be mounted in a confined environment.
2. Description of the Prior Art
In the context of this application, a microstrip-type antenna is one that is generally well known in the prior art as comprising a conductive ground plane or reference surface over which a reasonantly dimensioned conductive radiator "patch" is disposed.
In the past the radiating element or radiator "patch" of microstrip antennas have been generally edge fed or probe fed. For example, a probe fed microstrip antenna is described in U.S. Pat. No. 4,613,868 to Michael A. Weiss wherein a dual slotted microstrip antenna structure has an impedance matching slot and centrally located feed points with each feed point being a probe type feed point.
An edge fed microstrip antenna array is described in U.S. Pat. No. 5,017,931 for use at millimeter wave frequencies which radiates and receives a broadside beam of energy in which a first symmetric edge-fed array has its radiating elements physically interleaved with the radiating elements of a center-fed array.
Occasionally a microstrip antenna will have a mounting requirement which necessitates a different feed point from the desired or designed electrical feed point which is typically at an edge of the radiating "patch". For example, an antenna housing may have the antenna's feed connector constrained at a location in the housing that does not coincide with the designed electrical feed point for the antenna's radiating "patch". This requires a modification to the antenna's radiating "patch" design to accommodate a difference in location between the microstrip antenna's structural feed point and its designed electrical feed point while maintaining the antenna's microwave signal and radiation pattern.